Flatiron with anticipator



M y 8, 56 F. H. LA BREE 2,744,993

FLATIRON WITH ANTICIPATOR Filed Feb. 28, 1952 6 SheetsSheet 1 FIG. I

W FIG. 2

HVVNTOR FREDERICK H. LA BREE PAM-M0 BMW/4 ATTONNIY May 8, 1956 F. H. LA BREE FLATIRON WITH ANTICIPATOR 5 Sheets-Sheet 2 Filed Feb. 28, 1952 ll/l INVENTOR FREDERICK H. LABREE I TTGRNE'Y y 8, 1956 F. H. LA BREE 2,744,993 FLATIRON WITH ANTICIPATOR Filed Feb. 28, 1952 6 Sheets-Sheet 3 INVENT'OR FREDERICK H. LABREE May 8, 1956 F. H. LA BREE FLATIRON WITH ANTICIPATOR 6 Sheets-Sheet 4 Filed Feb. 28, 1952 IN VE' IV TOR m 8; m2 mm: mm. Q a .(Gr v H [Ti I} N2 N we 91 Q m9 N: 2.1 02 m a E K m N2 u ow N9 we FREDERICK H. LABREE May 8, 1956 F. H. LA BREE 2,744,993

FLATIRON WITH ANTICIPATOR Filed Feb. 28, 1952 5 Sheets-Sheet 5 I30 I32 I34 I58 INVENTOR FREDERICK H. LA BREE Ema 1.; 6. QM

A T TOR/V5 Y United States Patent 2,744,993 FLATIRON WITH ANTICIPATOR Frederick H. La Bree, Anoka, Minn., assignor, by mesne assignments, to Illinois MeGraw Electric Co., a corporation of Illinois Application February 28, 1952, Serial No. 273,927 3 Claims. (Cl. 21925) The present invention is concerned with electric fiatirons, and more particularly with an improved combination of such a flatiron with an anticipator for the thermal control switch.

Electric fiatirons are well known in which the sole plate is heated by an electric heating unit under the control of a thermally-responsive switch. The switch opens and closes in response to increase and decrease of the soleplate temperature and thus maintains the soleplate at an average temperature predetermined by the particular adjustment of the switch.

In many electric irons, the normal relative location and rrangement of the soleplate, heating element and thermally responsive switch are such that during the initial warm-up of the iron, the thermal switch is slow to respond and the soleplate temperature initially overshoots the desired operating temperature by a considerable margin. Such overshoot may cause initial ironing temperatures high enough to damage the particular fabric for which the switch has been set.

Various proposals have been made for the elimination of such overshoot. For example, it has been suggested that the thermally-responsive portion of the switch be subjected to direct radiation from the heating element. It has also been proposed that some sort of direct metallic heat-conducting path be provided from the heating element to the region in which the thermally-responsive member is located. It has also been suggested that the thermally-responsive switch be mounted on a terminal of the heating unit so that heat from the unit will reach the thermostat directly.

While a number of these suggestions have substantially eliminated the danger of overshoot in the initial warm-up of the fiatiron, the added influence of the heating element directly on the thermally-responsive switch tends to make such a switch less responsive to temperature conditions at the bottom of the soleplate. For example, once the iron has been warmed up, and the ironing operation starts, the bottom surface of the soleplate may be cooled immediately by contact with the material to be ironed, but it will require a substantial period of time before the cooling effect overcomes the direct flow of heat from the heating element to the thermally-responsive switch and closes the switch to supply heat once again to the soleplate. Thus the previous solutions of the overshoot problem during initial heating have been accompanied by the introduction of another problem, that of slower response of the switch to soleplate temperatures during ironing operations.

The combined problem of initial overshoot and slow response to changes in the lower surface temperature of the soleplate during ironing has particularly handicapped the use of so-called package thermostats in electric flatirons with soleplates of cast-iron or other material which does not conduct heat rapidly. Such thermostats have the advantage that they can be completely assembled as a separate thermal switch and can be calibrated prior to insertion in the flatiron. In practice, however, it has been found that such separate units either have more tendency to overshoot or are less responsive to the soleplate conditions during ironing than a thermal switch in which the thermally-responsive member is connected integrally in some manner with a portion of the soleplate or in which the soleplate itself is used as the thermallyresponsive member.

With these problems of the prior art in view, it is accordingly one object of the present invention to provide an improved combination of flatiron soleplate, electric heating unit, and thermally-responsive switch.

It is a further object to provide such a combination in which an anticipator and thermally-responsive control member are incorporated in such a manner as substantially to eliminate the problems of initial overshoot and poor temperature response during ironing.

l further object is the provision of an anticipator which can be used for the substantial reduction or elimination of overshoot in a preassembled thermally-responsive switch unit, without adverse effect on the responsiveness of such unit to fiatiron soleplate temperatures.

Still another object is the provision of a flatiron having an anticipator for elimination of overshoot, the anticipator and thermally-responsive switch of such iron being constructed and located in a specific manner insuring rapid response of the switch to changes in the soleplate temperature during ironing.

Other objects and advantages will be apparent from the following specification in which certain embodiments of the invention have been described.

in the drawings which form a part of this application, and in which like reference characters indicate like parts,

Figure l is a top view of a flatiron incorporating one embodiment of the present invention, with the flatiron cover and handle removed for clearness.

Fig. 2 is a partial sectional view on the line 2--2 of Fig. 1.

Fig. 3 is a perspective view of the heat anticipator of Figs. 1 and 2.

Fig. 4 is a sectional view on the line 4-4 of Fig. 1 prior to completion of the assembly of the device of Fig. 1.

Fig. 5 is a sectional view similar to Fig. 4 after completion of the soleplate and switch assembly.

Fig. 6 is a top view similar to Fig. 1 showing another embodiment of the present invention.

Fig. 7 is a side view of the device of Fig. 6 with certain soleplate and handle portions shown in section along the line 7-7 of Fig. 6.

Fig. 8 is a perspective view of the anticipator plate of Figs. 6 and 7.

Fig. 9 is a sectional view on the line 9-9 of Fig. 6, during an intermediate stage of assembly of the device, and

Fig. 10 is a sectional view on the line 10-10 of Fig. 6 after completion of the assembly.

As shown in Fig. l, the device includes a flatiron soleplate indicated generally at 18. The upper surface 20 of the soleplate includes a heating unit area 26 extending longitudinally along each edge of the soleplate. As shown more specifically in Figs. 4 and 5, each heating unit area includes a cavity or recess indicated at 28 and 28'. In this particular embodiment separate heating units are utilized at each edge of the soleplate and are connected in circuit in the manner described below. For convenience, only one of these units will be described.

Within the heating element recess 28, a heating unit indicated generally at 30 is located. This heating unit includes a resistance element 32 of the well-known fiat, Wound type protected by upper, lower, and intermediate layers of insulation 34. The heating unit includes a metallic sheath 35 having a cover member 36 held within the sheath or body 35 by inturned flanges 37 at the upper edges of the sheath. The other heating unit 30' has similar elements 32, 34', 35, 36', and 37'.

As shown in Figure 1, one terminal 38 of the heating 'ice unit 30' is connected to a terminal strip 4-0 for connection to one of the externalsupply leads of the fiatiron. At the opposite end of the'iron, the remaining terminal :42 of heating unit 30 isiconnected by a conducting strip 44 to one :terminal 46 of a thermally responsive switch 48. The other terminal 50 of switch 43 is in turn con- ;nected by conducting strip 52 to one terminal 53 of .the opposite heating unit 30'. The remaining terminal 55 of heating unit 30' is then provided with a terminal strip 54 forconnection to the remaining external supply lead. An electric circuit from the terminal strips 40 and 54 will accordingly be completed through both heating units 30 and 30 Whenever the thermal switch 48 is 'closed. The circuit will be interrupted whenever the switch is open.

In order to control the temperature of operation of the flatiron soleplate, the thermal switch 48 is mounted on a suitable control area 56 on the upper surface of soleplate' 18. This control area 56 is substantially parallel to the power soleplate surface 58 which constitutes the ironing surface of the appliance. ()ontrol area 56 also has substantial length and breadth and thus constitutes a flat control area on which the control elements of the iron may be suported in good heat-conducting engage- -ment. This control area may be in any specific location on the upper surface which has the temperature characteristics desired for control of the iron. Here the area is at the'forward central'region of the iron between the heating units.

Switch 48 includes a thermally-responsive control member 60 which extends across the soleplate control area 56 over a substantial length. Control member 60 is of the type which does not bend or flex upon change in temperature. This control member is, however, free to expand and contract in a plane parallel to the control area 56 and soleplate ironing surface 58 so that all portions of the control member 60 will remain in the same thermal relationship to the ironing surface at all times. In the particular example shown, control member 60 is in the form of a plate having not only substantial length, but also substantial breadth across the soleplate control area.

To convert the expansion and contraction of plate 60 into operation of the switch, an arch or bridge 62 is connected, as by spot welding, at its ends 61 to opposite ends of the plate 60. The arch or bridge member 62 is formed of material having a relatively low coefficient of thermal expansion, while the control plate 60 has a relatively high coeflicient of thermal expansion. Thus, upon expansion of plate 60 the central portion of the low expansion arch 62 will be drawn downwardly toward control member 60. At the center of this arch an insulating button 63 engages the lower contact arm 64 of the thermal switch. This lower contact arm is supported on terminal 50 and is biased downwardly so that it will follow at all times the up and down movement of the insulating button 63 in response to longitudinal contrac "tion or expansion of control plate 60.

The switch includes an upper contact arm 66 supported from terminal 46. This contact arm is biased upwardly and its particular setting is determined by engagement with an insulating button 68 in the lower end of an adjusting shaft 70. Shaft 70 is threaded into the switch .cas'ing at 72 and this threaded engagement provides up .and down movement of the shaft 70 and insulating button 68 in response to rotation of shaft 70. A stop member 74 on shaft 70 engages a post or abutment 76 on the casing to limit the extent of this adjustment. Rotation of control shaft 70 will therefore raise or lower the upper contact arm 66 to determine the particular soleplate temperature at which the contacts will open and close as the lower contact moves down or up in response to ex- .pansion and contractionof plate 60.

Switch 48 includes a casing 78 enclosing the top, sides,

and ends of the switch mechanism. The ends 80 of this casing portion are connected by screws 82 with upturned lips on the ends of the expanding and contracting control plate 60. Thus the thermal switch unit may be completely preassembled and calibrated and then mounted in the fiatiron as a unit. The end walls 80 of the switch casing include horizontal flanges 84 at their lower edges through which bolts 86 are threaded into the soleplate 18 to retain the switch in position.

While the heating units 30 and 30 may be held in position primarily by the close metal-to-metal engagement of the respective parts including sheath 35, cover 36, and the walls of recess 28, a bridge 88 is preferably provided to prevent the heating unit from working out of its recess. The retaining bridge 88 includes a crossbar 90 which is held downwardly against the soleplate by bolts 92 passing through the crossbar 90 and threaded into the soleplate itself. At each end of crossbar 90 are provided longitudinally-extending arms 94 and 96 engaging the covers 36 and 36' of the heating units 30 and 30' respectively. Arms 94 and 96 of the bridge member 38 may engage the covers at selected points so that the tension of bolts 92 holds the bridge and the heating units in position with respect to the soleplate.

According to the present invention a heat-anticipating member is constructed and located to provide a direct, metallic heat-conducting path from the covers 36 and 36 of the heating units to the soleplate control area 56. For convenience in insuring good thermal contact of the heat anticipator with the heating unit covers, the anticipator may be located beneath the ends 08 and 100 of the bridge member arms 94 and 96. This anticipator 102 includes a flat central area 104 corresponding substantially in length and breadth to the soleplate control area 56, or at least to that portion of the area covered by the thermal control plate 60 of switch 48. Anticipator 102 also includes portions 106 and 108 extending away from the central area 104 at each side for engagement with the heating unit cover portions 36 and 36.

In this particular embodiment of the invention, the soleplate control area 56 is located at a different level from the bottom of heating unit recess 28 and also from the top surface of cover 36 of the heating unit. Thus the side portions 106 and 108 of the anticipator are deformed downwardly from the central area 104 to insure thermal engagement with the heating units. Initially, the extent of this downward deformation is greater than the particular vertical spacing between the soleplate control area 56 and the level of the top of heating element covers 36 and 36.

When the anticipator 102 is initially positioned on the flatiron as shown in Figure 4, with the switch 43 loosely placed in position above the anticipator, the extra deflection of side portions 106 and 108 will hold the central area 104 of the anticipator spaced somewhat above the soleplate control area 56. This spacing is indicated at 110. When the retaining screws 86 for the thermal switch 43 are tightened downwardly, the thermal control plate 60 is forced down against the central area 104 of the an ticipator and this area in turn is clamped tightly against the soleplate control area 56 as shown in Fig. 5.

Thus the thermal control plate 60 and anticipator plate portion 104 are superimposed on each other and on the soleplate control area 56 in close face-to-face metallic engagement throughout their respective areas. The parts are in good thermal contact at all points longitudinally of the control plate 60 so that regardless of expansion and contraction of this control plate, it will reflect accurately the temperature conditions which reach it from the soleplate and from the anticipator. The location of the anticipator portions 106 and 108 beneath the ends 98 and 10! of the bridge member alsoinsures close thermal engagement of the anticipator with the heating element covers as shown in Fig. 5.

Anticipator 102 is made of material having a relatively high thermal conductivity, i. e., in the range of thermal conductivity of copper and aluminum. In the device of Figs. 1-5, beryllium copper has been used successfully for the anticipator plate, with a brass control plate and a cast-iron soleplate. For reasons noted below, however, an anticipator of higher conductivity, such as aluminum, may be preferred in certain cases.

In one preferred form of the invention, this thermal conductivity should also be higher than that of the material used for the expanding and contracting control plate 60, wherever possible. For example, brass and certain stainless steel alloys are often used for the control plate because of their favorable thermal expansion coefficients. (Aluminum, although it has a high thermal expansion coefficient, is not customarily used as a thermally-responsive control member because of its unfavorable creeping charactertistics.) High expansion brass and stainless steel control members, on the other hand, have a heat conductivity substantially less than that of aluminum and one-fourth to one-third that of copper. The present invention contemplates the use of materials such as aluminum and copper, and their alloys of high heat conductivity, for the anticipator member, in order that the anticipator may conduct heat directly to all areas of the control member faster than the heat would be conducted through the control member itself.

Another preferred feature of the present invention is the use of a relatively soft metal for the anticipator plate, in order that this anticipator plate may conform slightly to any roughness in the surface of control area 56 which results from the casting process by which the soleplate is formed. Here again, the brass and stainless alloys normally used for the thermally-responsive control member have a surface hardness which does not accommodate itself to such casting irregularities in the soleplate control area. It is therefore preferable that the anticipator be located between the control plate and soleplate and that it be made of material having a lower surface hardness than the material of the thermal control plate, in order to improve the metal-to-metal contact from soleplate to control plate. An anticipator plate of aluminum, for example, provides particularly advantageous operating characteristics, when located between a soleplate and control plate of harder materials, such as the cast-iron soleplate and the brass control plate mentioned above.

In the device of Figs. 1 through 5, the anticipator plate 162 not only provides a direct path for conduction of heat from the heating unit covers to the entire area of thermal control plate 60, thus substantially reducing or eliminating overshoot during initial warm-up of the iron, but the close face-to-face engagement of the plates and the control area throughout the area of the control plate 60 makes the control plate readily responsive to changes in temperature of the soleplate during ironing. Thus the correction of adverse overshoot characteristics is achieved, without sacrifice of the desired quick thermal response of the switch to soleplate temperatures during ironing.

Another embodiment of the present invention is shown in Figs. 6 through 10. In this example, the flatiron soleplate is indicated generally at 118. The upper surface of this soleplate is designated at 120. The soleplate has a pointed forward end 122 and a curved rear end 124.

The upper surface 129 of soleplate 118 includes a heating element area 126 which in this case extends lengthwise at each edge of the soleplate as well as across the forward edge thereof. This heating element area 126 includes a recess or groove 128, the bottom of which is substantially circular and accommodates the sheathed heating element 13% of well-known type. As illustrated in Fig. 9, heating element 130 includes a coiled resistance wire 132, embedded in ceramic material 134, which is enclosed in an outer cover or sheath 136. This element is pressed into the groove 128 and may be retained there,

either as the result of the pressure initially used in its introduction, or by means of some separate holding device.

One terminal 138 of the covered or sheathed heating unit 130 is connected to a terminal strip or conductor 140. The other terminal 142 of the covered heating element 139 is connected by a conducting strip 144 to one terminal 146 of the thermally-responsive switch 148. The other terminal 154) of switch 148 in connected by a conducting strip 152 having a terminal portion 154 for connection to an external electrical circuit,

in the desired area of the upper surface of soleplate 113, a substantially flat recessed control area 156 is provided. This control area 156 extends over a substantial length and breadth of the upper surface of the soleplate between the portions of heating element area 126 at opposite sides thereof. According to this embodiment of the invention, the control area 156 is located as close as possible to the lower surface 158 of the soleplate 118, in order that the temperature characteristics of the control area 156 will very closely reflect the temperature characteristics of the soleplate surface 158, particularly during ironing operations. The depth of this recess must be limited, however, so as to leave sumcient thickness beneath the control area to preserve a normal scorch pattern for the iron. In other Words, there must be enough metal to equalize and spread the heat from unit and thereby heat the lower soleplate surface 158 uniformly.

The thermally-responsive switch used in the present embodiment of the invention is basically similar to that described in connection with the previous example. This switch includes a thermally-responsive member 160, which has a relatively high coefiicient of thermal expansion and which extends throughout a substantial length of the soleplate control area 156. Member 169 also has substantial breadth and is thus in the form of a plate parallel to the soleplate bottom surface 158 and free to expand and contract longitudinally of the fiatiron in response to increase and decrease of temperature in the soleplate control area.

The arch or bridge member 162 is made of material with a relatively low coefiicient of expansion and has its ends spot welded to the high expansion plate at spaced points along the length of the plate as indicated. Opening 163 in plate 160 may be provided beneath the center of the low expansion arch 162 in order that the spacing of the arch from the high expansion plate may be properly adjusted at the time the arch is spot welded in position.

The switch itself includes a lower contact arm 164 electrically connected to terminal 146, and an upper contact arm 166 connected to terminal 150. The lower contact arm 164 is biased downwardly as before, and its vertical position will thus be controlled by the vertical position of the insulating member at the center of arch 162. This position, in turn, will depend upon the relative expansion and contraction of the thermally-responsive plate 160.

The position of upper contact arm 166 may be adjusted by change in the vertical position of insulating button 168 in the lower end of adjusting shaft 170. This shaft is threaded at 172 into the upper casing of the thermal switch unit and is provided with a stop 174 engaging a post 175 to limit the maximum adjustment of the switch.

A control shaft 178 extends upwardly from the shaft portion 176 through a recess 180 in the front handle post 132 of the flatiron handle 184. A control knob at the upper end of shaft 178 permits manual rotation of the shaft to adjust the vertical position of insulating button 168 and of upper contact arm 166.

Handle 184 also includes a rear handle post 188 having a recess 1% in which connections 192 are made between the terminal portions 140 and 154 and the external electric supply cord 194.

In the thermal switch itself, the contact arms 164 and 166 and their terminals 146 and 150 are supported on the top wall of a box-like upper casing 196. The depending front and rear walls of this box-like casing or enclosure sponsive control plate 160.

overlap upturned lips on the thermally-responsive plate 160 and the parts are secured together at the ends of the unit-by screws 198 and'200,-respectively. It will be untrol plate 160, unexpandable arch 162, and casing 196, as Well as adjusting shaft 170, may be preassembled, calibratedand then introduced into the iron as a separate subassembly or unit.

According to the present invention an anticipator plate 202 is associated with the soleplate control area 156, the thermally-responsive plate 160, and the heating unit 139. This anticipator plate is illustrated in Fig. 8 and includes a central area 204 of substantially the same length and breadth as the control area 156 and the thermallyre- In this example, since the control area 156 is recessed below the level of the upper surface of cover 136 of the heating unit, the area 204 of the anticipator plate 202 is correspondingly recessed. Vertical walls 206 and 208 at either side of this recess connect the central area 204 with laterally projecting wingsor extensions 208 and 210. These extending portions 20? and 210 project outwardly for engagement with the top of heating unit cover 136. These side extensions or portions 208 and 210 extend longitudinally of the iron substantially the same distance as the central area 204 and thus engage the top of the heating unit along a line of contact as indicated by the dotted lines 212 and 214 in Fig. 6.

In this embodiment of the invention, a portion of the vertical Walls 206 and 208 and the side extensions or portion 208 and 210 may be cut out as indicated at 216 and 218 to accommodate the clamping means for the thermally-responsive switch unit. This clamping means includes bolts 220 and 222 threaded into the upper surface of the soleplate and holding a crossbar or clamp 224 in position above the top of switch 148.

In order to insure good thermal contact between the anticipator plate portions 208 and 210 and the top cover 136 of the heating unit, the anticipator plate is initially formed with the central area 204 downwardly offset from the extending portions 208 and 210 by a verticaldistance which is slightly less thanthe actual difference in vertical levels between the control area 156 of the soleplate and the top of the heating element covers .136. Thus when the anticipator plate is first placed on the soleplate, as illustrated in Fig. 9, the central area 204 ofthe anticipator plate will be spaced slightly above the control area asshown at 226. As illustrated in this figure, the bolts 220 and 222 have not yet been tightened downwardly to clamp the parts in their fully assembled position.

When these bolts are tightened completely, they will force the clamp 224 downwardly, thus pushing the switch 148, including its control plate 160, down against the central area 204 of the anticipator plate and in turn clamping the latter in close face-to-face engagement with the soleplate control area 156 throughout the area of the latter. During this clamping operation the anticipator plate 202 will be slightly deformed so that the extending portions 208 and 210 are displaced upwardly and held in resilient engagement with the top of the heating element cover 136 along the lines of contact previously discussed. The resilient engagement between the extending portions 208 and 2100f the anticipator plate will thus insure the existence of a metal-to-rnetal contact which will provide a goodheat-conducting metallic path from the heating element cover through the anticipator plate extensions 208 and 210 to the central area 204 beneath the thermally-responsive control plate 160 of switch 148.

Heat can thus flow directly from opposite sides of the soleplate control area, directly from the heating element cover to the area of plate 160. This heat path is not limited to one particular portion of the plate but, because of the longitudinal extent of side portions 208 and 210, the anticipator plate brings heat directly into all portions along the length of the control plate 160. Since the heat is also brought simultaneously toeachside of'the control-plate, and sincethe central area- 204 of the anticipator plate is at all'times in close face-to-faceem gagement against the thermally-responsive control plate 160 throughout the entire area, all portions of the control plate 160 will be thermally influenced by theheat brought directly from the heating element covers by means of the anticipator.

At the same time, since the plates 160 and 204 are superimposed on the control area 156 in close face-to-face engagement with each other and with the control area throughout such area, there will be a direct metal-to-metal heat-conducting path from the bottom158 of soleplate perpendicularly (i. e., by the shortest path) to all areas of the switch control plate 160. The use of a soft metal for the anticipator improves this heat-conducting path through limited local deformation of the anticipator surface to accommodate irregularities on the surface of the soleplate control area.

In the embodiment shown, in Figs. 6-10, an aluminum anticipator is used between a cast-iron soleplate and a brass thermal control plate. Thus even though the anticipator plate portion 204 is located between the thermallyresponsive plate 160 and the soleplate control area 156, the metal-to-metal contact of these parts throughout the area, and the relatively high thermal conductivity and low surface hardness of the plate portion 204, result in close coordination of the temperatures of the soleplate bottom 153 and the switch control plate 160.

Some of the materials discussed above and their characteristics are as follows: 2

Material Heat Conductivity Hardness Control Plate: Brass .28 Cal. per sq. Cm. ASTMB-36 Alloy 8.

per See. per C.

Rockwell B-75-85.

Anticipator:

Aluminum 3-S (pre .39 Cal. per sq. Cm. Rockwell B-65-75.

ten-ed) per Sec. pcr C.

or Beryllium Copper .25 Cal. per sq. Cm. Rockwell 13-70.

per Sec. per C. .117 Cal. per sq. 0111.

per Sec. per 9 C.

soleplate: Cast Iron Brinnell 179-212.

As this list indicates, the aluminum anticipator has higher thermal conductivity and lower surface hardness than the brass control plate or the cast-iron soleplate according to one preferred form of the invention. The beryllium copper anticipator also has the desired lower surface hardness, although its heat conductivity is just slightly less than that of the brass control plate.

With respect to operation of the embodiments of the invention described above, the anticipator plate is believed to substantially reduce or eliminate intial overshoot during the first warm-up of the iron to a particular operating temperature, because it is no longer necessary for the heat from the heating element'130 to be conducted laterally through the soleplate to the control area 156. Obviously such a path is longer than the vertical distance from the heating element to the bottom surface 158 of the soleplate. Therefore certain portions of the soleplate bottom, without the present invention, would become unduly hot before the control area 156 reached a temperature which would open the switch and cut off the heat to the unit 130, particularly where the soleplate is formed of material, such as cast-iron, which does not conduct heat rapidly.

Furthermore, even after the switch opens, the heat stored initially in the heating unit would tend to raise .the soleplate temperature higher. In contrast, the anticipator of the present invention conducts heat to open the switch a predetermined time before the soleplate reaches the desired ironing temperature in its initial warm-up. Thus the stored heat in the element brings the soleplate nearer the desired temperature without excessive overshoot. In other words, the anticipator plate provides a highly conductive metallic path for feeding some of the heat from the heating unit 130 directly to the control plate 160 and throughout the area of the latter, before the control plate would otherwise receive such heat.

While this additional heat path through the anticipator could thus be expected to reduce or eliminate overshoot during initial warm-up of the iron, it would also be normally expected that conduction of this additional heat to the thermally-responsive plate 160 would make the plate less likely to respond to changes in the temperature of the lower soleplate surface 158 during ironing. It is therefore surprising that the parts can be arranged according to the present invention, so that the response of the control plate 160 to temperature changes at the bottom soleplate surface 158 is rapid and effective, and the use of a preassembled thermal switch is made practical.

The fact that the control plate 160, anticipator plate portion 204, and control area 156 are in close metal-tometal contact throughout their respective areas at all times, and the fact that the anticipator plate is of relatively high thermal conductivity and low surface hardness compared to the thermal control plate are believed to be important factors in this response. Thus, while the anticipator plate does conduct heat to the thermally-responsive control plate 160 of the switch, it may also be said to conduct heat to the central portion of the flatiron and thus improve the distribution of heat to the soleplate. By the same token, temperature conditions in the soleplate beneath the control area 156, whether they involve gain or loss of heat, can be readily reflected in the temperature of the control plate 160 because of the good conductivity of the intermediate anticipator plate portion 204 and the close thermal engagement between this anticipator and the thermal control plate and soleplate control area. Regardless of the theory involved, however, the fact remains that the relative construction and arrangement of the parts as described and claimed in the present invention does not only eliminate or substantially reduce overshoot during initial warm-up of the iron but also provides an iron which is quickly responsive to changes in soleplate temperature during ironing.

Since minor variations and changes in the exact details of construction will be apparent to persons skilled in this field, it is intended that this invention shall cover all such changes and modifications as fall within the spirit and scope of the attached claims.

Now, therefore, I claim:

1. An electric flatiron comprising a soleplate having a bottom ironing surface and a top surface including a substantially fiat control area and an electric heating unit mounted on said upper surface at opposite sides of the control area and having a metallic cover exposed at the top of the soleplate, an anticipator plate of relatively high thermal conductivity extending across substantially all of said control area and having portions engaging the cover of said heating unit at each of said sides of the area, and a thermal electric switch in circuit with the heating unit, said switch having a control member extending along a substantial length of the control area and free to expand and contract and thereby open and close the switch in response to increase and decrease of temperature in said area, said control member, anticipator plate and soleplate control area being in superimposed, face-to-face engagement during temperatureresponsive expansion and contraction of the control member and thereby providing a direct metallic heatconducting path from both the heating-unit cover and the bottom of the soleplate to each portion along the length of the control member within said area, said control member comprising a plate extending across a substantial length and breadth of the control area, the anticipator plate being located between the control plate and soleplate, and the anticipator-plate portions which engage the heating-unit cover extending along the cover a distance substantially corresponding to the length of the control area, the anticipator plate having its control-area portion and heating-rmit-cover-engaging portions at relative levels insuring engagement of said cover-engaging portions with the cover before the controlarca portion engages the control area, and means clamping the control member against the control-area por ion of the anticipator plate and thereby holding the latter in face-'to-face engagement with the control area with said heating-unit-engaging portions in resilient contact with the heating-unit cover.

2. An electric flatiron according to claim 1 in which the soleplate control area is recessed below the upper surface of the soleplate and in which the anticipator plate is similarly recessed throughout said area, the depth of said recessed portion being initially less than the difference in level between the heating-unit cover and the control area, and means clamping the control member against the recessed portion of the anticipator plate and the control area and thereby holding the anticipator plate in face-to-face engagement with the control area and in resilient engagement with the heating-unit cover.

3. An electric flatiron comprising a soleplate having a bottom ironing surface and a top surface including a substantially flat control area and an electric heating unit mounted on said upper surface at opposite sides of the control area and having a metallic cover exposed at the top of the soleplate, an anticipator plate of relatively high thermal conductivity extending across substantially all of said control area and having portions engaging the cover of said heating unit at each of said sides of the area, and a thermal electric switch in circuit with the heating unit, said switch having a control member extending along a substantial length of the control area and free to expand and contract and thereby open and close the switch in response to increase and decrease of temperature in said area, said control member, anticipator plate and soleplate control area being in superimposed, face-to-face engagement during temperatureresponsive expansion and contraction of the control member and thereby providing a direct metallic heatconducting path from both the heating-unit cover and the bottom of the soleplate to each portion along the length of the control member within said area, said control member comprising a plate extending across a substantial length and breadth of the control area, the anticipator plate being located between the control plate and soleplate, and the anticipator plate portions which engage the heating-unit cover extending along the cover a distance substantially corresponding to the length of the control area, clamping means applying a clamping force to at least a part of the control-area portion of the anticipator plate for thereby holding the latter in face-toface engagement with the control area and the heatingunit-engaging portions in resilient contact with said heating-unit cover, the anticipator plate having said part of its control-area portion and its heating-unit-engaging portions at relative levels insuring engagement of said heating-unit-engaging portions with the heating-unit cover before said part of the control-area portion engages the control area.

References Cited in the file of this patent UNITED STATES PATENTS 2, 2 3 3 6 l 5 

